Yes you right from some research i did they dont go for much the 28” & 30” barrelI've had a couple, one with a 28" and the other had a 30" barrel. Not bad shotguns at all. Never saw one with a longer barrel. Only problem was these new cheap built shells that seem to have odd rim sizes and the shell stops had trouble catching them but I didn't blame the gun for that. In ordinary times I'd say about $175-$200 for a regular length barrel. In these crazy times it's anybody's guess.
Yes they are not that common I occasionally look for one but didn t come across any yetHeck of a nice, heavy gun. Looked a lot like the Model 12, if the 120 is the one you're referring to.
Marlin barrels were very well made. I had the "Goose Gun" with 36" barrel and though unwieldy, would dump drakes well out past the dekes. And, as usual, I didn't answer the question.
In ten years, 2008-2018, we had two come through the shop, one with the 40". It sold quickly at $495. This was about 2017 and it was only about 80%. I'd guess about the same today if 90% and you don't care about parts availability on a low production number gun.
Yes you re right there wasn t a high demand for them back thenThere never was much demand for them, probably less today. But at the same time since there was never much demand, they didn't make many. It may take a while to find someone who wants one for the novelty of it, they may pay a premium.